The present invention relates to an air-conditioning control device for a vehicle.
In the air-conditioning control device for the vehicle, a cool-air generator including a compressor, a condenser and an evaporator and a hot-air generator with a heat source of engine cooling water are provided, and conditioning air having a specified temperature is obtained by changing the mixture ratio of the cool air and the hot air. This conditioning air is supplied into a vehicle compartment by a blower fan, in which the amount of the supplied conditioning air is adjusted by changing a rotational speed of the blower fan. Generally, the above-described compressor is driven by an engine and a water pump to circulate the cooling water is driven by the engine as well. Accordingly, when the engine stops, the compressor and the water pump are stopped, so that the cool-air generation function and the hot-air generation function stop.
Further, in the air-conditioning control device for the vehicle, an automatic air conditioning, in which an actual temperature inside the vehicle compartment is automatically controlled at a target temperature, becomes the mainstream. The automatic control of air conditioning is conducted based on parameters representing a vehicle-compartment inside environmental condition, a vehicle-compartment outside environmental condition, and an air-conditioning operational state by a driver (especially, setting of the above-described target inside temperature), so that the conditioning-air supply temperature, a conditioning-air outlet, the conditioning-air supply amount and others are adjusted automatically.
Meanwhile, some vehicles have recently adopted a so-called idling stop (start stop) which automatically stops the engine in order to improve the fuel economy (gas millage) when the vehicle travels at a considerably-low speed or during a vehicle stop. The idling stop is executed when a predetermined start condition is met (satisfied). Herein, this start condition is generally configured such that some conditions including zero vehicle speed (vehicle stopping), brake operating, no accelerator operating, a shift range of D-position, and others are all met, for example.
In a vehicle provided with a roof which is configured to be open and closed, such as an open car, an air conditioning mode is changeable in vehicle states: between a roof-open state and a roof-closed state, as described in Japanese Patent Laid-Open Publication No. 2001-88537. Herein, an inside/outside air mode, in which the control is conducted based on a target supply temperature, is selected in the roof-closed state, but an inside air mode is forcibly selected regardless of the target supply temperature in the roof-open state. The mode control described in the above-described patent document aims to maintain the air-flow amount supplied from an outlet of an air-conditioning unit at a constant value regardless of the vehicle speed by selecting the intake air mode in the roof-open state.
Herein, demand for the air conditioning in the roof-open state where the driver tends to enjoy traveling, feeling the outside air, may be relatively low, compared to a case of traveling in the roof-closed state. Meanwhile, if an idling-stop condition for stopping the engine automatically by the idling stop is configured to be the same between the roof-open state and the roof-closed state, the roof-open state with the lower air-conditioning demand may have less opportunity of automatically stopping the engine by the idling stop. Therefore, it may be considered that the idling-stop condition for the roof-open state is relaxed so as to make the idling stop to be relatively easily attained, compared to the roof-closed state, thereby increasing the opportunity of automatically stopping the engine.
Relaxing the idling-stop condition so as to make the idling stop to be relatively easily attained as described above is preferable in improving the fuel economy. By contrast, if the operation of the air-conditioning device stops, which is caused by the automatic stop of the engine by the idling stop, the passenger may be easily influenced by the outside-air temperature or the solar radiation because the roof is open, so that the passenger may have uncomfortable feelings improperly (the passenger's demand for the air conditioning may not be met).